1. Field of the Invention
The present invention relates to a bus bar substrate for an interior light of a vehicle. The bus bar substrate is installed in an interior light mounted to the inner side of a roof of the vehicle. A bus bar is mounted to the bus bar substrate in order to supply power to a lamp when a switch is operated, such as when a door is opened.
2. Description of the Related Art
A related circuit for turning on a lamp in an interior light of a vehicle comprises bus bars (used for connecting a power supply, a switch, and the lamp) fitted to grooves disposed in the back surface of a base formed by injection molding. Such a circuit is disclosed in, for example, U.S. Pat. No. 6,402,570 (the entire content of which is expressly incorporated hereinto by reference). Switching on the switch causes the power supply and the lamp, disposed in the base, to be connected by the bus bar, thereby turning on the lamp.
In the interior vehicle light as described above, the circuit is a simple circuit used only for turning on and off the lamp in the base. Therefore, it is possible to form the circuit only by using the bus bar in the back surface of the base. An increasing number of recent vans have interior lights for each of three rows of seats, that is, a front seat (driver's seat), a rear seat, and an intermediate seat disposed between the front seat and the rear seat. There is a therefore a demand for separately controlling the flashing of the interior lights at the rear seat and at the intermediate seat by operating a switch installed at the interior light at the driver's seat.
In order to separately control the interior lights at the three rows of seats, a sophisticated circuit is formed. Therefore, when bus bars are disposed only at the back surface of the base, unless the bus bars are crossed, it becomes impossible to construct a circuit network for controlling the flashing of the lamps or it becomes very difficult to design a circuit pattern.